This invention relates to a process and apparatus for packing bulk commodities, such as carcases or parts of carcases of animals, and other foodstuffs, in vacuum packs for distribution for example to the wholesale food distributors.
In packing foodstuffs for example in this manner the operator places the product such as a part of an animal's carcass into a premade bag of sealable plastics material and the loaded bag is placed into the sealing apparatus. This apparatus comprises a platform or indexing conveyor disposed on a suitable frame or stand with a removable lid or hood which is usually hinged to one side of the tray opposite to the loading position, and a sealing bar is disposed across the tray adjacent to the loading position. When the loaded bag is laid in the platform or conveyor the operator disposes the mouth of the bag over the sealing bar and the hood is closed. A second sealing bar is mounted on the hood so that when the hood is closed the hood sealing bar engages the mouth of the bag and through the bag mates with the platform or conveyor sealing bar. Reduced pressure is applied to the chamber so that the bag is under vacuum of usually about 4 Torr and the electric current is supplied to the sealing bars thus sealing the bag as by impulse sealing under reduced pressure. The closed chamber is then ventilated and the lid is opened so that the sealed pack can be transported to a station for further processing or storage. The hood is preferably actuated as by calibrated springs which urge it into the open position and the current to the sealing bars is cut off at the same time.
In this process there is the problem that at the end of the operation leaks in the packs may occur at the seal so that air enters the packed bags through an imperfect seal which leads to a number of packs being rejected. This is an expensive wastage.
It is known to use a bag of shrinkable plastics material and then the unsealed bag with the commodity in it is placed in a dip tank filled with water usually at about 100.degree. C. although it is not necessary for this water to boil. At this temperature the bag shrinks onto the commodity and the shrunken bag is put in the vacuum sealing apparatus.
The main object of the present invention is to provide an improved process and apparatus suitable for packing bulk food products and other commodities in which the aforesaid disadvantages are minimised and also to provide improved bulk packs produced by this process.